A5058712183- Astro and Planetary Science
- Planetary Science and Exploration
- Methane Hydrates and Related Phenomena
- Geology and Paleoclimatology Research
- Space Exploration and Technology
- Atmospheric and Environmental Gas Dynamics
- Space Science and Extraterrestrial Life
- Atmospheric Ozone and Climate
- Isotope Analysis in Ecology
- Astrophysics and Star Formation Studies
- Paleontology and Stratigraphy of Fossils
- Spaceflight effects on biology
- Hydrocarbon exploration and reservoir analysis
- Groundwater and Isotope Geochemistry
- Scientific Research and Discoveries
- Atmospheric chemistry and aerosols
- Solar and Space Plasma Dynamics
- Geological and Geochemical Analysis
- Seismic Imaging and Inversion Techniques
- Origins and Evolution of Life
- Amino Acid Enzymes and Metabolism
- Chemical Analysis and Environmental Impact
- Molecular Spectroscopy and Structure
- Hydraulic Fracturing and Reservoir Analysis
- Microfluidic and Bio-sensing Technologies
Goddard Space Flight Center
2012-2024
NASA Exoplanet Science Institute
2018
Universities Space Research Association
2013
University of Arizona
2006-2008
Planetary Science Institute
2005-2008
University of Colorado Boulder
2001-2006
Laboratory for Atmospheric and Space Physics
2003-2006
University of Waterloo
2005
Pennsylvania State University
1999-2001
University of Colorado System
2001
Mass-independent fractionation (MIF) of sulfur isotopes has been reported in sediments Archean and Early Proterozoic Age (> 2.3 Ga) but not younger rocks. The only mechanism that is consistent with the data on all four involves atmospheric photochemical reactions such as SO2 photolysis. We have used a one-dimensional model to investigate how isotopic produced during photolysis would transferred other gaseous particulate sulfur-bearing species both low-O2 high-O2 atmospheres. show atmospheres...
Earth appears to have been warm during its early history despite the faintness of young Sun. Greenhouse warming by gaseous CO2 and H2O itself is in conflict with constraints on atmospheric levels derived from paleosols for Earth. Here we explore whether greenhouse methane could important. We find that a CH4 mixing ratio 10(-4) (100 ppmv) or more Earth's atmosphere would provide agreement paleosol data 2.8 Ga. Such concentration readily maintained methanogenic bacteria, which are thought an...
The Sample Analysis at Mars (SAM) investigation of the Science Laboratory (MSL) addresses chemical and isotopic composition atmosphere volatiles extracted from solid samples. SAM is designed to contribute substantially mission goal quantitatively assessing habitability as an essential step in search for past or present life on Mars. a 40 kg instrument suite located interior MSL's Curiosity rover. instruments are quadrupole mass spectrometer, tunable laser 6-column gas chromatograph all...
Research Article| May 01, 2005 Massive release of hydrogen sulfide to the surface ocean and atmosphere during intervals oceanic anoxia Lee R. Kump; Kump 1Department Geosciences, Pennsylvania State University, 535 Deike Building, University Park, 16802, USA Search for other works by this author on: GSW Google Scholar Alexander Pavlov; Pavlov 2Center Astrobiology, Laboratory Atmospheric Space Physics, Colorado, C.B. 392, Boulder, Colorado 80309-0392, Michael A. Arthur 3Department 538 Author...
Abstract The Sample Analysis at Mars (SAM) instrument on board the Science Laboratory Curiosity rover is designed to conduct inorganic and organic chemical analyses of atmosphere surface regolith rocks help evaluate past present habitability potential Gale Crater. Central this task development an inventory any molecules elucidate processes associated with their origin, diagenesis, concentration, long‐term preservation. This will guide future search for biosignatures. Here we report...
Reports of plumes or patches methane in the martian atmosphere that vary over monthly time scales have defied explanation to date. From situ measurements made a 20-month period by tunable laser spectrometer Sample Analysis at Mars instrument suite on Curiosity Gale crater, we report detection background levels atmospheric mean value 0.69 ± 0.25 parts per billion volume (ppbv) 95% confidence interval (CI). This abundance is lower than model estimates ultraviolet degradation accreted...
We show that the escape of hydrogen from early Earth's atmosphere likely occurred at rates slower by two orders magnitude than previously thought. The balance between slow and volcanic outgassing could have maintained a mixing ratio more 30%. production prebiotic organic compounds in such an would been efficient either exogenous delivery or synthesis hydrothermal systems. soup oceans ponds on Earth favorable place for origin life
A single scoop of the Rocknest aeolian deposit was sieved (< 150 µm), and four separate sample portions, each with a mass ~50 mg, were delivered to individual cups inside Sample Analysis at Mars (SAM) instrument by Science Laboratory rover's acquisition system. The samples analyzed separately SAM pyrolysis evolved gas chromatograph spectrometer analysis modes. Several chlorinated hydrocarbons including chloromethane, dichloromethane, trichloromethane, chloromethylpropene, chlorobenzene...
Variable levels of methane in the martian atmosphere have eluded explanation partly because measurements are not repeatable time or location. We report situ at Gale crater made over a 5-year period by Tunable Laser Spectrometer on Curiosity rover. The background mean value 0.41 ± 0.16 parts per billion volume (ppbv) (95% confidence interval) and exhibit strong, seasonal variation (0.24 to 0.65 ppbv). This is greater than that predicted from either ultraviolet degradation impact-delivered...
We determined radiogenic and cosmogenic noble gases in a mudstone on the floor of Gale Crater. A K-Ar age 4.21 ± 0.35 billion years represents mixture detrital authigenic components confirms expected antiquity rocks comprising crater rim. Cosmic-ray-produced (3)He, (21)Ne, (36)Ar yield concordant surface exposure ages 78 30 million years. Surface occurred mainly present geomorphic setting rather than during primary erosion transport. Our observations are consistent with deposition shortly...
The Deep Atmosphere Venus Investigation of Noble gases, Chemistry, and Imaging (DAVINCI) mission described herein has been selected for flight to as part the NASA Discovery Program. DAVINCI will be first incorporate science-driven flybys an instrumented descent sphere into a unified architecture. anticipated scientific outcome new understanding atmosphere, surface, evolutionary path possibly once-habitable planet analog hot terrestrial exoplanets. primary design features preferred launch in...
Research Article| January 01, 2003 Methane-rich Proterozoic atmosphere? Alexander A. Pavlov; Pavlov 1Center for Astrobiology, Laboratory Atmospheric and Space Physics, University of Colorado, 392 UCB, Boulder, Colorado 80309-0392, USA Search other works by this author on: GSW Google Scholar Matthew T. Hurtgen; Hurtgen 2Astrobiology Center, Department Geosciences, Pennsylvania State University, Park, 16802, James F. Kasting; Kasting Michael Arthur Author Article Information Publisher:...
Hydrodynamic escape is an important process in the formation and evolution of planetary atmospheres. Transonic steady state solutions time-independent hydrodynamic equations are difficult to find because existence a singularity point. A numerical model developed study neutral gas from atmospheres by solving time-dependent equations. The validated against analytical solution isothermal atmosphere. uses two-dimensional energy deposition calculation instead single-layer heating assumption,...
The late Archean atmosphere was probably rich in biologically generated CH 4 and may well have contained a hydrocarbon haze layer similar to that observed today on Saturn's moon, Titan. Here we present detailed model of the photochemistry formation early atmosphere, examine effects such climate ultraviolet radiation. We show thickness limited by negative feedback loop: A optical depth more than ∼0.5 visible would produced strong “antigreenhouse effect,” thereby cooling surface slowing rate...
Recent exploration by the Cassini/Huygens mission has stimulated a great deal of interest in Saturn's moon, Titan. One Titan's most captivating features is thick organic haze layer surrounding believed to be formed from photochemistry high CH(4)/N(2) atmosphere. It been suggested that similar may have on early Earth. Here we report laboratory experiments demonstrate properties likely form through Titan and We used deuterium lamp initiate particle production these simulated atmospheres UV...
The deuterium-to-hydrogen (D/H) ratio in strongly bound water or hydroxyl groups ancient martian clays retains the imprint of formation these minerals. Curiosity's Sample Analysis at Mars (SAM) experiment measured thermally evolved and hydrogen gas released between 550° 950°C from samples Hesperian-era Gale crater smectite to determine this isotope ratio. D/H value is 3.0 (±0.2) times standard mean ocean water. ~3-billion-year-old mudstone, which half that present atmosphere but...
Significance Carbon isotopic analysis is among the most pervasive geochemical approaches because fractionation of carbon isotopes produces a natural tracer biological and chemical processes. Rover-based analyses sedimentary rocks on Mars have potential to reveal modes Martian cycling. We report values methane released during pyrolysis samples obtained at Gale crater. The show remarkable variation indicating different origins for evolved from samples. Samples multiple locations within crater...
Research Article| November 01, 2001 Organic haze in Earth's early atmosphere: Source of low-13C Late Archean kerogens? Alexander A. Pavlov; Pavlov 1Department Geosciences, Pennsylvania State University, University Park, 16802, USA Search for other works by this author on: GSW Google Scholar James F. Kasting; Kasting Jennifer L. Eigenbrode; Eigenbrode Katherine H. Freeman Author and Article Information Publisher: Geological Society America Received: 09 Mar Revision 22 Jun Accepted: Jul First...
Bringing phosphorus to life: The prebiotic origin of key biomolecules such as RNA and ATP is contingent on a source condensed phosphates, pyrophosphate triphosphate. Condensed phosphates can be produced at high yields from the oxidation H-phosphonate or H-phosphinate. Reactive were likely abundant early earth's surface, setting stage for chemistry that led evolution life. Supporting information this article available WWW under http://www.wiley-vch.de/contents/jc_2002/2008/z802145_s.pdf...
Amino acids are fundamental to life as we know them the monomers of proteins and enzymes. They also readily synthesized under a variety plausible prebiotic conditions common in carbon-rich meteorites. Thus, they represent reasonable class organics target search for chemistry or chemical evidence on Mars. However, regardless their origin, amino other organic molecules present near-surface regolith rocks Mars can be degraded by exposure cosmic rays that penetrate depth few meters. We exposed...